In cellular telecommunication systems such as 3GPP-based systems (e.g. the EPS and 2G/3G-GPRS) or non-3GPP based systems (e.g. HRPD and WiMax) that employ dynamic Policy and Charging Control (PCC), there is a function known as the PCEF, Policy Charging and Enforcement Function. The PCEF interacts with a function in the system known as the OCS, the Online Charing System, suitably over an interface known as the Gy interface.
In addition, the PCEF also interacts with another function, known as the PCRF, the Policy and Charging Rules Function, which is suitably done over an interface known as the Gx interface.
In recent updates of the 3GPP specifications, a node known as the BBERF, the Bearer Binding and Event Reporting Function, has been introduced. The BBERF performs so called bearer management in the Access Network, and carries out event reporting to the PCRF over an interface known as the Gxx interface. The BBERF interacts with the PCEF via an interface known as the S5/S8 interface that is based on Proxy Mobile IP, PMIP, protocol.
The PMIP protocol is only capable of providing the PCEF with limited information regarding session related events in the system events which the OCS uses as input when performing so called credit authorization.
Since the Gy interface terminates at the PCEF, the limited information regarding events in the system which can be provided to the PCEF from the BBERF will also reflect on the information which can be provided to the OCS, which may be a source of problems.